13 views (last 30 days)
Show older comments
Ken on 10 Apr 2024
-
-
Link
Direct link to this question
https://webchat.mathworks.com/matlabcentral/answers/2105236-building-an-array-of-strings-that-might-be-empty
Edited: Stephen23 on 10 Apr 2024
Open in MATLAB Online
I want to make an array of four elements, containing the contents of four edit fields, which might potentially be empty. First try:
app.graphLimits = [app.XminEditField.Value, app.XmaxEditField.Value, ...
app.YminEditField.Value, app.YmaxEditField.Value]
But no! This syntax appears to concatenate the strings, and if the fields are all empty, the result is precisely one empty string.
Second try:
app.graphLimits(4) = app.YmaxEditField.Value;
app.graphLimits(1) = app.XminEditField.Value;
app.graphLimits(2) = app.XmaxEditField.Value;
app.graphLimits(3) = app.YminEditField.Value;
But no! It complains with an error message that I really don't understand
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
What? I'm trying to initialize and pre-allocate an array of four elements, the fourth of which is (in this case) an empty string.
What am I missing? What is the correct syntax to accomplish what I'm trying to accomplish?
0 Comments Show -2 older commentsHide -2 older comments
Show -2 older commentsHide -2 older comments
Sign in to comment.
Sign in to answer this question.
Answers (3)
Fangjun Jiang on 10 Apr 2024
⋮
Open in MATLAB Online
That is because app.XminEditField.Value and etc are char array, not string
use string()
s=["a","","b","c"]
s = 1x4 string array
"a" "" "b" "c"
c=['a','','b','ded']
c = 'abded'
c=[string('a'),string(''),string('b'),string('ded')]
c = 1x4 string array
"a" "" "b" "ded"
1 Comment Show -1 older commentsHide -1 older comments
Show -1 older commentsHide -1 older comments
Fangjun Jiang on 10 Apr 2024
Direct link to this comment
https://webchat.mathworks.com/matlabcentral/answers/2105236-building-an-array-of-strings-that-might-be-empty#comment_3127521
Open in MATLAB Online
Or a little easier this way. But have to put in whitespace ' ', not ''
c=['a';' ';'b';'d']
c = 4x1 char array
'a' ' ' 'b' 'd'
s=string(c)
s = 4x1 string array
"a" " " "b" "d"
Sign in to comment.
the cyclist on 10 Apr 2024
Open in MATLAB Online
If the fields are empty strings, your first syntax will not concatenate them. It will make them into a string array:
app.XminEditField.Value = "";
app.XmaxEditField.Value = "";
app.YminEditField.Value = "";
app.YmaxEditField.Value = "";
app.graphLimits = [app.XminEditField.Value, app.XmaxEditField.Value, ...
app.YminEditField.Value, app.YmaxEditField.Value]
app = struct with fields:
XminEditField: [1x1 struct] XmaxEditField: [1x1 struct] YminEditField: [1x1 struct] YmaxEditField: [1x1 struct] graphLimits: ["" "" "" ""]
Are you possibly using character arrays and not strings? (I'm guessing yes.)
Can you upload a small example of the data you are working with?
0 Comments Show -2 older commentsHide -2 older comments
Show -2 older commentsHide -2 older comments
Sign in to comment.
Stephen23 on 10 Apr 2024
Edited: Stephen23 on 10 Apr 2024
Open in MATLAB Online
"What am I missing?"
The differences between strings and characters. Do not mix up string arrays with character vectors (which is what you probably have), they are completely different things with very different properties:
https://www.mathworks.com/help/matlab/characters-and-strings.html
"What is the correct syntax to accomplish what I'm trying to accomplish?"
Use a cell array (rather than concatenating all of the character vectors together like you tried):
app.graphLimits = {app.XminEditField.Value, app.XmaxEditField.Value, ...
app.YminEditField.Value, app.YmaxEditField.Value};
1 Comment Show -1 older commentsHide -1 older comments
Show -1 older commentsHide -1 older comments
Stephen23 on 10 Apr 2024
Direct link to this comment
https://webchat.mathworks.com/matlabcentral/answers/2105236-building-an-array-of-strings-that-might-be-empty#comment_3127606
Edited: Stephen23 on 10 Apr 2024
Open in MATLAB Online
"I'm trying to initialize and pre-allocate an array of four elements"
The code you show does not preallocate anything. But the error is very easy to reproduce:
a(1) = 'hello'
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
The reason is very simple: you are trying to force multiple characters into one element of a character array. One element of a character array holds exactly one character, thus what you are attempting will not work.
Sign in to comment.
Sign in to answer this question.
See Also
Categories
MATLABLanguage FundamentalsData TypesCharacters and Strings
Find more on Characters and Strings in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
An Error Occurred
Unable to complete the action because of changes made to the page. Reload the page to see its updated state.
Select a Web Site
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .
You can also select a web site from the following list
Americas
- América Latina (Español)
- Canada (English)
- United States (English)
- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)
- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- Deutsch
- English
- Français
- United Kingdom(English)
Asia Pacific
- Australia (English)
- India (English)
- New Zealand (English)
- 中国
- 日本Japanese (日本語)
- 한국Korean (한국어)
Contact your local office
